I have more than 4000 hours and I think the number of hours played isn't a warranty of a good post on the forum.
If you can't get an alliance with a major power, then just grow with other minor, give them lands in peace deal, with them growing with you, you can defeat easily any major country. It's normal for a major power to refuse an unhelpful alliance with a minor nation, you shouldn't be bother by it.
It's curious that you need to restart 10 times. It seems you're restarting until you're in a good enough starting position that you can quickly jump into the action - that is, declare your first easy war within 25 years.
As a tiny minor it's not uncommon to start the game with only another minor or two as allies, and then waiting half a century or more for your first opportunity to declare a war that you aren't nearly guaranteed to lose. It's years and years of doing mostly nothing - unless you've a neighboring bully that claims your clay.
I don't restart if I can't get alliances or jump in to a war straight away, I play until 1)I get Conquered or 2) Feel like I've barely expanded/developed by the late 1400s normally the first option happens before the second. As an example I tried Byzantium the other day and I think I did 10 starts. 2 of them actually started OK, Venice declared a trade war on my since I had them embargoed and I was able to take all Venetian lands in Greece the Balkans including there vassals land. None of it mattered tho since in every single run by 1450 Ottomans had declared war on me, wiped my army and I was being sieged down all because I couldn't get 1 decent Alliance to deter them for a couple of years. Like I expect to do at least a couple of restarts as Byzantium thats to be expected but 10 really? That's just one example, it happens when I try to play other minors near superpowers as well, I could play all these minors 2 patches ago but it was still a challenge and not easy at all maybe a restart or 2 due to bad RNG but I was fine with that.